The function of the Protein Expression and Peptide Core facility is to provide proteins and peptides needed by the program project. The Specific Aims are: 1. To provide recombinant and other proteins to projects, including but not limited to single chain antigen receptor molecules, tetramers, and fusion proteins. 2. To provide peptides and peptidic constructs bearing proteins to project, including but not limited to peptides, especially long and hydrophobic antigen peptides, and peptide templates bearing protein and peptide ligands. David Kranz lab will provide those reagents listed under Specific Aim 1. In the first year this will include pepMHC tetramers and T cell receptor tetramers. In subsequent years it will include these reagents and additional cytokine fusion proteins.